The present invention relates to the food processing arts. It finds particular application in conjunction with the post-pasteurization, surface microbial decontamination of hot dogs, sausages, and other processed meat and poultry products prior to packaging, and will be described with particular reference thereto.
Prevention of food poisoning is of paramount importance in the food processing industry. Concern for food safety has lead most countries to regulate the food industry heavily to minimize public health risks. Despite these efforts, food poisoning still occurs. Many instances of food poisoning are attributed to bacteria, such as Salmonella, Clostridium, and Staphylococcus, among others.
Of rising concern is the relatively recent increase in the Listeria contamination of poultry and processed food products, such as frankfurters, other sausages, cheese, dairy food, and seafood. Processed meat and poultry products such as frankfurters are generally cooked to destroy harmful bacteria. Of particular concern is the discovery that pasteurized and fully cooked processed foods are being contaminated with microbes, such as Listeria monocytogenes, following cooking or pasteurization and prior to packaging for point of sale. Such contamination is typically surface contamination and is believed to be caused by the contact of microbes with food surfaces subsequent to heat treatment. Microbes, such as Listeria, may be airborne (i.e., carried by dust) or present on food contacting surfaces, such as processing equipment.
Recently, several outbreaks of food poisoning have been reported in which the causative agent was suspected to be or identified as Listeria-contaminated food. Listeriosis is a serious disease which may cause meningitis, spontaneous abortion, and perinatal septicaemia. Although treatable with early diagnosis, untreated Listeriosis exhibits a high mortality rate. In 1998, twenty deaths were associated with a Listeria epidemic. Regulations now specify that food should be absolutely free of Listeria, any contamination is considered to be an adulteration and the food should not be placed in commerce.
Food preservation by inhibition of growth of Listeria monocytogenes is difficult. Listeria is a particularly difficult microorganism to destroy because it is heat resistant and is able to grow, even under refrigeration, in raw and cooked products. Methods for destroying the organism on raw and on processed foods have included treatments using heat, radiation, chemicals, or antibiotics. In the heat and irradiation treatments, the food products are subjected to the heat or radiation after packaging. However, the heat resistance of the organism makes it difficult to achieve complete kill through heat.
Antibiotics, such as Streptococcus lactis-derived or synthetic equivalent bacteriocin, such as nisin, have been used, either as a spray, or dip, or as a film on the packaging or casing which remains in contact with the food during heat treatment.
Chemicals used in treating the food products include ammonium compounds and acids such as citric, lactic, acetic, and peracetic acid, which have been used to wash down meat carcasses. With the chemical treatment methods, the carcass is placed on a conveyer system and the decontaminating chemical is sprayed over the items as they pass beneath. Liquid smoke has been used on pasteurized processed foods to inhibit recontamination after cooking.
Processed meats, such as sausages and deli meats, are usually microbially decontaminated during the cooking or smoking process. It is generally assumed that the cooked product remains free of microorganisms during the subsequent decasing, slicing, and packing stages. However, the occurrence of outbreaks of food poisoning associated with these precooked products has lead the present inventors to recognize that the cooked food products are recontaminated with pathogenic bacteria, such as Listeria, either through airborne contact or through contact with contaminated equipment or packaging materials.
The present invention provides for a new and improved system and process for treating food products which overcome the above-referenced problems and others.